You're right. - Rita

I'm with you on this. This is typical ridiculous behavior of bad managers. Their job is to hire enough staff to cover. As a professional with an agreed upon schedule, you should receive a polite request from them and nothing more. Not whining, not turning blue and stamping their feet. They need to go offer someone enough money to work that shift. If they can't do that, then it's not you who should be punished.